Hydraulic machine for deforming sheet metal



Dec. 29, 1970 P. CAILLOUX 3,550,425

HYDRAULIC MACHINE FOR DEFORMING SHEET METAL Filed July 24, 1968 3Sheets-Sheet 1 q- +--u E: I 2 TI 2 N r- N I i I H2]? I I I 1 1H" J .1!.-J

FIG.1

P. CAILLOUX 3,550,425

HYDRAULIC MACHINE FOR DEFORMING SHEET METAL Dec. 29, 1970 3 Sheets-Sheet2 Filed July 24, 1968 FIG.3

P. CAILLOUX 3,550,425

HYDRAULIC MACHINE FOR DEF'ORMING SHEET METAL Dec. 29, 1970 Filed July24, 1968 3 Sheets-Sheet 5 United States Patent 3,550,425 HYDRAULICMACHINE FOR DEFORMING SHEET METAL Paul Cailloux, Le Perreux, France,assignor to Promecan Sisson-Lehmann, Saint-Denis, France, a French bodycorporate Filed July 24, 1968, Ser. No. 747,330 Claims priority,application France, July 26, 1967, 115,702 Int. Cl. B21j 9/12 US. Cl.72--453 8 Claims ABSTRACT OF THE DISCLOSURE The present inventionrelates to hydraulic machines for deforming or working sheet metal, suchas shears, presses in general, and in particular folding pressescomprising a fixed bolster and a moving bolster.

To ensure in such machines a regular movement of the moving bolstertowards the fixed bolster, various hydraulic thrust and synchronizingdevices are known in which jacks perform these two functions separatelyor otherwise.

For maintaining the moving bolster parallel to the fixed bolster,devices are known comprising two correcting jacks located on each sideof the longitudinal axis of the machine, these jacks, of the double-rodtype and having two equal chambers, are interconnected by two crossedconduits so that they are self fed for movements in the same directionand of the same amplitude. Devices of this type are also known in whichthe two crossed conduits are also fed in such manner that apredetermined inclination of the moving bolster relative to the fixedbolster can be maintained during the stroke and that possible leakagesor reduction in the volume of oil due to compression can be compensated.Several control means are known for these corrections and in particularthat employing, as an indicator of angular deviations between the twobolsters, a flexible element such as a ribbon one end of which isconnected to the fixed frame of the machine where as the other end actson a distributor feeding the two crossed conduits, whereby any angulardeviation results in an action of equal value but of opposite directionof the correcting jacks.

However, these corrections are insufiicient to maintain with precisionthe two bolsters parallel or at a predetermined angle therebetween sincethe adopted devices do not compensate the elastic bending of certainresisting parts of the frames under stress and, above all, do notcompensate the opening or spreading apart of the side walls of swan neckor C-shape which bend in different ways when the loads are eccentric,that is, offset relative to the vertical median plane of the machine,and produce angular deviations which remain uncorrected and consequentlyhave an adverse effect on the precision of the work carried out.

The object of the invention is to remedy the aforementioned defects andinsufficieneies. The invention provides a machine for deforming sheetmetal, such as shears, presses, folding presses and the like, comprisinga fixed bolster and a moving bolster actuated by one or more jacks andequipped with a synchronizing system comprising two hydrauliccompensating devices which are fed by the action of an indicatorindicating angular deviations between the two bolsters which acts on adistributor valve which is so inserted in the hydraulic circuit that anyangular deviation between the holsters results in a correspondingmovement but of opposite direction of the hydraulic compensators. Inthis machine, the indicator, in addition to its usual functions ofmaintaining the parallelism and the predetermined angles between thebolsters, receives impulses which are proportional to deviations due tothe opening of the swan-neck side walls, that is, to differences in theelastic deformation of said side walls under stress, from a hydrauliccorrector comprising a part fixed to the frame of the machine and amovable part connected to said distributor, whereby said impulsesproduce an additional correction of the position of the moving bolsterrelative to the fixed bolster and nullify the consequences of thedeviations due to the opening of the side walls.

This machine also comprises a safety device which cuts off the supply ofthe motor of the machine as soon as the difference in the elasticdeformations of the side walls reaches a predetermined limit value.Thus, the arrangement according to the invention affords an automaticcorrection of all undesirable variations in the relative angularposition of the two bolsters of the machine while affording an essentialprotection against abnormal overloads. In a general way, the inventionresults in an improvement in the quality of the work produced andensures safety in operation.

Further features and advantages of the invention will be apparent fromthe ensuing description with reference to the accompanying drawings.

In the drawings:

FIG. 1 is a front elevational view of the assembly of a typical machineshowing the position of the main parts;

FIG. 2 is a side elevational view of the assembly of the machine;

FIG. 3 is a hydraulic diagram showing the indicator indicating angulardeviations and the system correcting the deviations;

FIG. 4 is a view of another version of the hydraulic correcting device,and

FIG. 5 is a corresponding electric circuit diagram.

As can be seen in FIGS. 1 and 2, the fixed frame 1 of the presentlydescribed machine comprises two transverse side walls 10, 1a to which issecured a fixed bolster 2, and two longitudinal walls 1a and 111 betweenwhich is movable a moving bolster 3 whose stroke or travel towards thefixed bolster 2 results from the action of thrust jacks or rams 4 whichbear against the walls 1a and 1b through journals 4a, 417.

It will be clear that in order to achieve this movement of the movingbolster, the thrust rams must be fed with oil under pressure. However,the driving source and the hydraulic circuit elements required forachieving a rapid approach, the working stroke, the return stroke andthe various stoppages, are not part of the present invention and arewell known in various forms. Consequently, they have not been shown ordescribed, Similarly, the electric diagram of the machine has been shownonly partially in FIG. 5.

In the described machine, the moving bolster 3 is made parallel to, orplaced at any other given angle relative to the fixed bolster 2, by theaction of two auxiliary jacks 3 which operate in opposite directions asshown in FIG. 3 and constitute compensating devices, The auxiliary jacks5 are connected by two crossed conduits or lines 22a and 23a in suchmanner that the chamber of one communicates with the chamber 21 of theother and vice versa.

These two conduits are connected by conduits 22b, 23b and 230 to twooutlet ports of a distributor slide valve 7 whose body is integral withthe fixed frame 1. One of two inlet ports of this valve is connected bythe conduit to the general tank of the machine and the other isconnected by the conduit 24 to the common supply conduit of the thrustrams 4 so that, if the auxiliary jacks 5 must be fed, they are fed undera pressure which is proportional to that prevailing in these rams.

One end of the slide of the valve 7 is connected to the fixed frame 1through a tension spring 9 and the other end is connected to a flexibleelement 10 which can be, for example, a wire, cable, chain or ribbonpreferably of steel. The valve 7 thus forms a part of the device thatcompensates for angular deviations of the bolsters.

In a first part of its path of movement, this flexible element 10travels round two rollers 11 and 12, the spindles of which are carriedby the fixed frame 1, and, between these rollers, round a roller 13whose spindle is carried by a yoke 14 controlled by a screwthreaded rod15 screwthreadedly engaged in a nut 17 which is integral with theframe 1. The rod is provided with a handwheel 16 for varying theposition of the roller 13 on the axis of symmetry between the tworollers 11 and 12 and consequently the length of the flexible element 10in this part of its path.

In a second part of its path, the flexible element 10 travels round tworollers 18 and 19 whose spindles are carried by the moving bolster 3 andlocated on a line which is substantially perpendicular to the directionof the movement of the moving bolster towards the fixed bolster 2.

In a third part of its path, the other end of the element 10 isconnected to the hydraulic correcting device, described hereinafter,which modifies the action of the element 10 on the valve 7 as a functionof the pressures admitted into the conduits 220 or 23c.

In the embodiment shown in FIG. 3, this hydraulic correcting device is adouble-rod jack 26 whose cylinder 27 is integral with the fixed frame 1and divided into two chambers 29 and 30 by a piston 28 having doublerods, these chambers being fed by way of the conduits 23c and 220,respectively. The piston 28 is biased to a midway position in its travelby two opposed compression springs 31 and 32 hearing against thecylinder 27. The action of the spring 31 opposes those of the springs 9and 32 and the piston 28 is therefore in static equilibrium while theflexible element 10 is under permanent tension. The assembly is adjustedin such manner that, in this situation, the position of the two rollers18 and 19 corresponds to a correct parallelism between the fixed andmoving bolsters 2 and 3 and that the slide of the valve 7 is exactly inthe midway position of its travel.

A block 33 integral with the piston 28 is adapted to actuatemicroswitches 34 and 35 of conventional break type integral with theframe 1 (FIG. 5). These microswitches cut off the current of themaintaining coil 36 of the main switch 44 of the motor-pump M and stopthe whole of the machine as soon as a given amplitude of the travel ofthe piston 28 is reached.

In a modification shown in FIG. 4, this hydraulic correcting deviceconsists of three pins 37a, 38b and 38c which are integral with thefixed frame 1 and on which are pivotable respectively a jack 38a, astraight lever 39 and a cranked lever 40. The other end of the jack 38ais connected to the end of the straight lever 39 by a pin 39a and asecond jack 38b is connected to the other end of the lever 39 by a pin39b and, moreover, to the cranked lever 40 by a pin 40a. Hooked onto thelever 40 4 is one end of the flexible element 10. The whole of thisarrangement is put under tension by the spring 9.

The jack 38a is fed by way of the conduit 23c and the jack 38/) by wayof the conduit 22c. These two jacks comprise two cylinders 41a and 41bto which are fixed two pistons 42a and 4212, respectively, by two rods43a and 4312 which become elastically extended as a function of thepressures prevailing in each jack and pivot the cranked lever 40 in onedirection or the other on its pin 370. In these movements, the lever 40actuates the microswitches 34 and 35 as soon as a predeterminedamplitude of movement has been reached and these switches stop the wholeof the machine as explained with reference to FIG. 3.

In the general assembly arranged in this manner, only the thrust rams '4are fed during the approach travel of the moving bolster 3, theauxiliary jacks 5 feeding themselves mutually by way of the conduits 23aand 22a for equal travels, since their sections are equal. However, assoon as any cause of disequilibrium appears and modifies the relativeangular position of the two bolsters, such as an eccentric load,dissymmetrical friction, leakages of oil in the auxiliary jacks 5, theimaginary line intersecting the axes of the rollers 18 and 19 tends tobecome inclined with the moving bolster 3 in the direction of theheaviest load and, in accordance with this inclination, acts on thevalve 7 through the element 10, For example, for an inclination of themoving bolster 3 in the counterclockwise direction, the slide of thevalve 7 descends so that the conduit 230 is connected to the dischargewhile the conduit 22c is fed. The two auxiliary jacks 5, which haveopposite directions of action, then produce a couple in the clockwisedirection, that is, in the direction opposed to that of the inclinationof the aforementioned imaginary line, this couple being maintained solong as the disequilibrium lasts and so long as the spindles of therollers 18 and 19 have not resumed their initial position.

The loading of the machine and the correction of the parallelism definedhereinbefore have thus put the conduits 22a, 22b, 22c under pressure andconnected the conduits 23a, 23b, 23c to the discharge. Consequently, inrespect of FIG. 3, the chambers 30 and 29' of the jack 26 arerespectively under pressure and connected to the discharge and this jack26 acts on the flexible element 10 in the same direction as that of thecause of this disequilibrium and this produces an additional correctingeffect. Similarly, in the embodiment shown in FIG. 4, the extension ofthe rod 43b produces the same action on the flexible element 10.

It should also be mentioned that this action is also proportional to themachine loading pressure which is defined by the pressure prevailing inthe suply conduit 24 and is consequently proportional to the elasticdeformations or openings of the branches of the vertical uprights 1c and1d of the machine. These openings are of extent DC and DC (FIG. 2) andhave no effect on the parallelism of the two bolsters in that they areof the same value at both ends of the bolsters and are not corrected inthis case, but only in this case. However, in the case of unequaldeformations, affecting the parallelism of the bolsters, they arecompensated by this additional correction of the feed to the auxiliaryjacks 5 in the suitable direction owing to the action of the jack 26.shown in FIG. 3, or of one of the jacks 38a or 38b shown in FIG. 4,through the flexible element 10 on the position of the slide of thevalve 7, since the elastic openings or deformations of the vertical sidewalls of the fixed frame are proportional to the differences between thesupported forces and therefore to the pressure differential prevailingin the auxiliary iacks.

It will be observed that owing to the action of the microswitches 34 and35 and the associated elements, such as 33 (FIG. 3) or lever 40 (FIG.4), operation of the machine is stopped as soon as the difference in thedeforma tions of the side walls 1c and 1d reaches a predetermined safetylimit.

It is possible, while remaining within the scope of the invention, toreplace the hydraulic correcting devices described hereinbefore by anyother hydraulic device having the same supply and the same effects onthe flexible element as those described. It could be desired to producepurposely an angular setting, such as 041 and 112 (FIG. 1), between thefixed bolster 2 and the moving bolster 3 in order to satisfy particularrequirements in the use of the machine. For this purpose, the hand wheel16 modifies the extent to which the flexible element 10 is engagedbetween the rollers 11, 12 and 13 so as to increase or reduce thislength and thus acts on the position of the slide of the valve 7 andmodifies the position of the moving bolster 3 by the described action ofthe j acks 5. This adjustment retains all the advantages concerning thealready described correction and maintenance of this relative positionof the moving bolster 3 and fixed bolster 2.

The machine according to the present invention consequently achieves adegree of operational precision in practice which is of particularinterest for the user while affording a remarkable protection of themain parts.

Although specific embodiments of the invention have been described, manymodifications and changes may be made therein without departing from thescope of the invention as defined in the appended claims.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. In a hydraulic machine for deforming sheet metal of the type having afixed bolster, a moving bolster supported on a fixed frame havingswan-neck lateral walls and a motor-pump unit for supplying oil underpressure from a tank to a hydraulic circuit which feeds at least onethrust ram, the movement of the moving bolster being controlled by ahydraulic synchronizing device which maintains said bolsters in apredetermined relative posi-- tion, said synchronizing device includinga hydraulic distributor valve, and means for operating said valve inresponse to angular deviation of one of said bolsters relative to theother bolster, the improvement comprising a correcting device, saidcorrecting device including means for modifying the effect of saidoperating means on said distributor valve in proportion to hydraulicpressure in said circuit, whereby the correcting device modifies theaction of said synchronizing device so as to compensate dilferences inthe elastic deformations of said lateral walls under load and thusmaintain said relative position of said bolsters.

2. A machine as claimed in claim 1, wherein said hydraulic synchronizingdevice comprises two jacks having four chambers and two crossed conduitsputting said chambers in communication with each other, said correctingdevice comprising two chambers which communicate with the respectiveconduits of said jacks of said synchronizing device and are defined byat least one piston,

said distributor valve having a slide valving element, said operatingmeans including a flexible element having one end connected to saidpiston and another end connected to said slide of said valve, wherebythe differences in the pressures in the conduits act through said valveon said synchronizing device so as to compensate the differences betweenthe elastic deformations of said lateral walls due to differences inload.

3. A machine as claimed in claim 2, wherein said two chambers of saidcorrecting devices are defined in a hydraulic jack having a double rodand having equal sections, s aid hydraulic jack having a cylinderintegral with said fixed frame and the piston being subjected to thecombined action of the traction exerted by said flexible element and theaction of a spring bearing against said cylinder and the opposed actionof a second spring also bearing against said cylinder.

4. A machine as claimed in claim 2, comprising a lever having two armsand pivotally mounted on a pin integral with said frame, a crank leverhaving two branches and pivotally mounted on a pin integral with saidframe, said two chambers of said correcting device being defined in twohydraulic jacks the first jack of which has a cylinder connected to apin integral with said fixed frame and a piston connected to one of saidarms of said lever, whereas the second of said hydraulic jacks has acylinder connected to the other arm of said lever and a piston isconnected to one of said branches of said cranked lever, the other ofsaid branches being connected to said flexible element of said operatingmeans.

5. A machine as defined in claim 4, wherein in each jack of saidcorrecting device the cylinder is rendered integral with thecorresponding piston by a centre rod which is capable of elasticextension in proportion to the pressure prevailing in the cylinder ofthe corresponding jack.

6. A machine as claimed in claim 1, wherein said machine includes adrive motor and said hydraulic correcting device comprises twomicroswitches adapted to stop said motor when a maximum permissibledifference between the deformation of said lateral walls is reached,said correcting device having a movable actuating element in position toactuate said switches.

7. A machine as claimed in claim 6, wherein said actuating element isprovided on one of the two piston rods of the single jack of saidcorrecting device.

8. A machine as claimed in claim 6, wherein said actuating elementincludes one of the branches of said cranked lever.

References Cited UNITED STATES PATENTS 2,484,908 10/1949 Purcell -2582,978,976 4/1961 Hazelton 100258 3,007,508 11/1961 Giordano l002143,120,799 2/ 1964 Strnad 10046 RICHARD J. HERBST, Primary Examiner G. P.CROSBY, Assistant Examiner US. Cl. XR. 72-386; l00258

